Courtesy: Amr Abdelgawad, Maimonaides Medical Centre, Brooklyn, NY, USA

Medial Parapatellar Approach

• Most common approach for total knee arthroplasty.
• Incision runs medial to the patella.
• May injure medial genicular arteries (superior and inferior).
• Additional damage during lateral release or meniscectomy can compromise patellar blood supply.
• May result in avascular necrosis of the patella.

Subvastus and Midvastus Approaches

• Subvastus approach avoids quadriceps tendon incision.
• Provides less surgical exposure compared to medial parapatellar approach.
• Midvastus approach splits the vastus medialis muscle.
• Midvastus approach has higher risk of quadriceps denervation.

Extension of Exposure

• Quadriceps snip extends incision laterally from proximal end of medial parapatellar approach.
• Does not significantly change postoperative rehabilitation.
• V?Y turndown (patellar turndown) allows larger exposure.
• Patellar turndown requires delayed active extension postoperatively.

Posteromedial Knee Approach

• Used for bicondylar tibial plateau fractures and PCL tibial inlay graft.
• Interval between semimembranosus tendon and medial head of gastrocnemius.
• Medial gastrocnemius protects the neurovascular bundle.
• Popliteal artery approximately 2 cm from PCL tibial fixation screw.

Posterolateral Knee Approach

• Used for lateral meniscus inside?out repair.
• Superficial interval between iliotibial band and biceps femoris.
• Deep dissection achieved by retracting gastrocnemius posteriorly.
• Provides access to posterolateral capsule.

Saphenous Nerve at the Knee

• Infrapatellar branch crosses from medial to lateral.
• Midline incision (e.g., ACL BTB graft) may injure this branch.
• Injury causes numbness on lateral side of knee.
• Knee flexion and hip external rotation reduce nerve injury risk during hamstring graft harvest.

Lateral Knee Anatomy

• Popliteus tendon runs deep to the lateral collateral ligament.
• LCL lies proximal and posterior to popliteus tendon insertion.
• LCL inserts into anterior fibular head.
• Popliteofibular ligament inserts into posterior fibular head.
• Biceps femoris inserts broadly along fibular head.

Popliteal Neurovascular Bundle

• Arrangement superficial to deep: tibial nerve ? popliteal vein ? popliteal artery.
• Popliteal artery is the deepest and most anterior structure.
• Popliteal artery lies about 1 cm from posterior tibial plateau in flexion.

Screw?Home Mechanism

• Locks the knee in full extension.
• Occurs due to difference in femoral condyle geometry.
• External rotation of tibia occurs in final 20–30° of extension.
• Popliteus muscle unlocks the knee via internal rotation of tibia.

Blood Supply of the Knee

• Derived from popliteal artery.
• Includes superior genicular, inferior genicular, and middle genicular arteries.
• Middle genicular artery supplies ACL and PCL.

ACL Anatomy

• ACL is intra?articular but extrasynovial.
• Primary function: prevent anterior tibial translation.
• Secondary function: limit internal tibial rotation.
• Highest tension occurs in full extension.
• Blood supply from middle genicular artery.

ACL Bundles

• Two bundles: anteromedial (AM) and posterolateral (PL).
• AM bundle tight in flexion.
• PL bundle tight in extension.
• PL bundle provides rotational stability.
• Bundles separated by the lateral intercondylar ridge.

Meniscus Anatomy

• Menisci composed mainly of type I collagen.
• Lateral meniscus is more mobile than medial.
• Menisci move anteriorly with extension and posteriorly with flexion.

Baker’s Cyst

• Occurs between semimembranosus tendon and medial head of gastrocnemius.
• Often associated with intra?articular knee pathology.